Dual protection turbine governor mechanism



Sept. 30, 1941. w. SCHMID 2,257,279

DUAL PROTECTION TURBINE GOVERNOR MECHANISM Filed Dec. 12, 1940 2 Sheets-Sheet l 35m WITNESSES.

5'! 5'6 7 35 INVENTOR fihhzwm '7 a9 WRLTER ScHMw.

ATTORNEY P 1941- w. SCHMID 2,257,279

DUAL PROTECTION TURBINE GOVERNOR MECHANISM Filed Dec. 12, 1940 2 Sheefs-Sheet 2 F'IG S.

: 3 i I I l M, r w I v 2:; 2: WITNESSES: i I INVENTOR 65 I 6a WRLTER Summk M I BY M M Qua,

ATTORNEY turbines of the first type.

Patented Sept. 30, 1941 DUAL PROTECTION TURBINE GOVERNOR MECHANISM Walter Schmid, Philadelphia, Pa., assignorto Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application December 12, 1940, Serial No. 369,784

Claims.

The invention relates to a prime mover, more particularly of the elastic-fluid turbine type, having a governor valve operated by a speed governor and an emergency valve closed in response to. operation of an overspeed trip device when overspeeding of the prime mover occurs, and it has for an object to provide apparatus of this character with mechanism affording dual overspeed protection for the prime mover, that is, in the event of overspeeding of the prime mover, not only does thetrip device operate to close the emergency valve but it also operates to bring about closing of the governor valve.

Heretofore, it has been common practice with turbines of the smaller type to have the governor valve operated directly by the governor lever without the interposition of a servo-motor or relay and to provide an independent emergency valve which is closed in response to operation of. an overspeed trip device. While it is old, with turbines of the larger type employing a servomotor or relay to operate the governor valve, to arrange for operation of the relay to close the governor valve in response to operation of the overspeed trip device to. close the emergency or throttle valve, so far as I am aware, this feature of dual protection has not been provided for To achieve this objective, I divide the linkage between the governor and the governor valve into first and second portions and provide means cooperating therewith so that the governor valve may be moved in opening and closing directions by the governor and so that the second portion may be moved independently of the first portion and the governor to move the governor valve in a closing direction, together with biasing means rendered effective by the emergency trip device to move the second portion and the governor valvein a closing direction independently of the thereto;

h Fig. 2 is an axial sectional view of apparatus shown in Fig. 1; V

Fig. 3 is a detail sectional view taken along the line III-III of Fig. 2;

, Fig. 4 is a detail View showing linkage between turbine, with the improved control mechanism applied the emergency trip device and the emergency valve;

Fig. 5 is a planview of apparatus shown in Fig. 2; and

Fig. 6 is a detail view taken along the section line VI-VI of Fig. 5.

Referring 'now to the drawings more in detail, the turbine, at IU, comprises a rotor H and a casing 12. The rotor carries an overspeed trip device [3 and a governor, at 14, disposed outwardly of the latter, the governor having an operating member l5 extending coaxially from one end of the rotor.

Steam is supplied to the lower half of the turbine casing by means of an elbow conduit having first and second leg portions Hi and I! provided with emergency and governor valves, at 20 and 2|, respectively.

As shown, the emergency valve, at 20, is of the butterfly type and it includes a butterfly valve member 22 and a housing 23. The butterfly member is carried by an operating shaft or spindle 24 fitting bearings in the housing 23, and the upper end thereof extends outwardly and above the housing for a purpose to be described. Biasing means, such as a torsion spring 26, exerts its force on the butterfly valve member to close the latter.

The governor valve, at 2|, is of the conventional balanced type, it including a housing having suitable seats provided in the second leg portion I! of the inlet conduit and a movable valve member 27 connected to a rod 28 extending outwardly through the elbow cap 29. v

The governor operating member I5 is connected to one end of the lever 3i], fulcrumed at 3| to an arm 32 carried by the hub extension 33 of the elbow cap 29, the other end 30a of the leverabutting against the outer end of the rod 28. A spring 34 is arranged between the outer end of the hub extension 33 and an abutment 35 on the rod, and it serves to cause the latter to follow the lever when the latter moves outwardly. Thus, the linkage or connection between the governor and the governor valve is divided into first. and second portions constructed and arranged to provide for movement of the governor valve in opening and closing directions by the governor and to provide for movement of the valve in a closing direction independently of the governor.

The. overspeed trip device I 3 operates in response to a predetermined overspeed, not only to close the emergency valve, at 20, but also to close the governorvalve, at 2|, thus providing dual protection, and apparatus for this purpose will now be described.

With the trip lever 31 in its normal or inward position, connections are provided between the normal or retracted position; however, when the trip lever is struck and moved outwardly from the rotor by the overspeed trip device l3, the connections are released, whereupon the springs are effective to close the valves,---and,when the emergency valve is again opened'and the trip lever and the governor valve closing spring are restored to their normal positions, the connections are re-established.

Referring to the connection between the trip lever 31 and the emergeny valve, at 20, this is comprised by a rock shaft 38, an abutment 39 on the rock shaft and engaging an abutment 49 on the'slide 4| for holding'the emergency valve open against the force of its spring 26, the slide having a transverse slot or groove 42 engaged by a pin 43 depending from the crank 44 connected to the emergency butterfly valve upper trunnion 24,the pin-and-slot connection providing for angular motion of the crank '44 with rectilinear motion of the slide 4|. Withdisengagement of themovable abutment 39 from the slide abutment 40, the spring 26 closes the emergency valve and moves the slide inwardly toward the turbine rotor.

"As shown, the slide 4| is in the form of a rod carried by suitable guide bearings 46. The slide rod has attached thereto a member 49 which slidingly overhangs the top of the butterfly valve housing to provide the slot or groove 42 conveniently located for the depending pin 43 with the butterfly valve, at 29, open. The rock shaf 38 is carried by a bearing 59.

To provide for suitable extent of engagement of the abutments 39 and 40, the arm 5| (Fig. 6) attached to the rock shaft and having the abutment 39 is' preferably provided with a set screw 52 which may be fixedly secured in adjusted position to vary the clearance'with respect leased, allows the spring to engage the abutments and then to close the governor valve. The cup abutment 56 is normally held, with the spring, in retracted position by means of a connection including the shoulder 58 (Fig. 3) formed on the abutment 56, a corner 59 engaging the shoulder and provided by the semi-circular portion 60 of the short rock shaft 6|, a crank 62 connected to the upper end of the latter, and a link 63 joining the crank 62 to the crank 64 depending from the rock shaft 38.

After closing of both the emergency and governor valves, at 26 and 2|, in response to operation of the overspeed trip device l3, it is necessary to open the emergency valve, at 20, and to retract the spring to restore admission of steam to the turbine under control of the governor, and means is provided to facilitate the accomplishment of these results. The butterfly valve crank 44 has a handle 65 for moving the butterfly valve from closed to open position, this movement being accompanied by outward movement of the slide 4| due to the pin-and-slot connection between the latter and the crank; and, when the butterfly valve reaches open position, the slide 4| will be moved outwardly sufficient-v ly so that the torsion spring 53 may move the rock shaft 38 to restore the trip lever 31 to its inward or normal position with the abutment 39 engaged behind the slide abutment 49. This movement of the rock shaft is also transmitted by the crank 64, the link 63, and the crank 62 to the rock shaft 6| to bring the corner 59 in position to engage behind the abutment shoulder to thesliderod 4|,whereby the extent of overlapping engagement of the abutments 39 and 40 may be varied, asdesired.

The'rock shaft 38 is biased by means of the torsion spring 53, to move the trip lever 31 to its inward or normal position with the abutment '39 engaging behind the slide abutment 49.

A tension spring 54 exerts its force on the slide 4! to avoid any-chatter orbacklash'of the parts. and to hold the slide in proper relation to the pin 43 so that, upon resetting, the pin 43 engages in slot or groove 42 automatically.

In order that closingmovement of the gov-' ernor valve, at 2|, may occur in response to operation of the 'overspeed trip device l3, the connection between the governor, at I4, and the governor valve includes: thrust abutting portions, as already described, so that the governor valve maybe moved in a closing direction independently of the governor; and, to provide for this independent movem'ent of the valve rod 28' in- V Wardly relatively to the lever 39, a compression spring 55 is located within the hub extension' 33,

the spring being held compressed by the "cup abutment 56f normally held spaced from' the abutment51on the rod 26 so that the latter is; freefor governor operation, but which, when re- 53 of the-cup abutment 56 when the latter and the spring 55 are in'retracted or normal position. As restoration of the spring 55 to its normal position free of the governor valve may not be concurrent with opening of the butterfly emergency valve, an elastic connection or element is provided to permit the rock shaft 38 to 'move immediately with movement of the rock shaft 6| delayed until the cup abutment and spring are retracted. To this end, the link 63.

extends through an'opening in the crank 64, an inelastic abutment 61 (Fig. 4) carriedby the link engages one side of the crank and an elastic abutment provided on the link engages the other side of the crank. As shown, the

elastic abutment is comprised by a compression spring 68 interposed between said other side of the' crankand an abutment 69 on the link;-

Should the cup abutment 56 and the spring;

55 not be retracted','-movement of the rock shaft 38 will occur without concurrent movement of the link 63; the spring 63being compressed; and, when the abutment andthe spring 'are retracted, the springs 6| a and fifl beingeffec-- tive to restore the link 63 to normal position and to position the corner 59: behind the shoul-e der 58. To retract the abutment 56 and the spring 55, there is provided aclever 1| fulcrumed to. the hub extension 33 and having aninner end portion 72 engageable with the abutment 5 6. and having an outer handle.portion '|3. V

From the f0reg0ing,.it will. be apparent that,

not only is dual protection provided by the, mechanism described, but'parts' of the turbineand oi the mechanism are so constructed andjlocatied that the arrangement as a .Whole is compact.

Dual protection assuring ofclosin gqf either the governor or the emergency valve should the other valve stick is provided by means of connections betweenthe emergency valve and the trip lever 75 and between the latter" and the spring for closing the governor valve, the connections including latches which are released when the trip lever is moved outward from its normal position by the overspeedtrip device in order that springs forthe emergency and governor valves may act independently to close the latter and which are re-engaged when the emergency valve is again opened, the spring for closing the governor :valve being retracted or restored to its normal position free of the latter when the trip lever is restored to its normal position. Assembly and maintenance are facilitated in that all of the parts are accessible and, do not interfere; and, asv the handles 13 and 85 are accessible at the same locality, the connections for overspeed closing of the valves may readily be separately tested. As suming that it is desired to test the emergency valve for closing without allowing, the governor valve to close, the operator moves the handle 13 outwardly bringing the inner portion 12 of the lever against the abutment 56 to hold the latter and the spring 55, in retracted position even though the corner 59 is disengaged from the shoulder 58 incident to tripping of the emergency valve. On the other hand, if it is desired to test the operativeness of the connection for closing of the: governor valve under overspeed conditions, without the emergencyvalvebeing closed, then i the handle 65 is held, to prevent closing of the latter valve and inward movement of the slide 4| upon tripping of the trip lever 3'7, and then the latter lever is trippedto release the spring 55 may close the governor valve. By having an elbow steam inlet conduit connected to the lower half of the casing, it is possible to have the rotor and the emergency and governor valve operating elements at different levels withthe emergency and governor valve operating elements arranged close together whereby the connections between the governor, the emergency trip device, and the valves are relatively simple and compact, with all of the parts conveniently accessible.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is:

1. In a steam turbine having a rotor and an elbow steam admission conduit with a first leg arranged at right angles to the rotoraxis and a second leg arranged parallel to the latter, a butterfly valve in the first branch and having a trunnion extending upwardly from the latter, a governor valve in the second branch and having a rod extending axially of and from the latter, a governor operated by the turbine, a member movable by the governor andhaving thrust abutting relation with said rod to provide for movement by the governor of the governor valve in a closing direction and to provide for movementv of the governor valve in a colsing direction independently of the governor, a first spring for normally maintaining the rod in abutting relation with respect to said member and serving to move the governor valve in an opening direction, a second spring for moving the butterfly valve in a closing direction, a slide extending parallel to the first branch and at right angles to the turbine rotor, a crank connected to said trunnion, a connection between theslide and the crank and providing for angular movement of the latter with rectilinear movementof the former, a firstlatch cooperating with the slide to hold the butterfly-valve open against the force of its spring, an overspeed trip device carried by the rotor, a rock shaft arranged parallel tothe rotor axis, a lever fixedly carried by the rock shaft and arranged to be moved away from the rotor by the overspeed trip device, a third spring exerting force on the rock shaft to turn the latter in the direction to move said lever toward the rotor, a first abutment on said rod, a second abutment engageable with the first abutment and movable to move the governor valve in a closing direction independently ofthe governor, a fourth spring exerting force onthe second abutment in the direction of the first abutment, a second latch for holding the second abutment spaced from the first abutment to provide for governor operation of the governor valve uninfiuenced by the fourth spring, and means responsive to movement of. the rock shaftby the overspeed trip device to release th first and second latches to provide for closing of the emergency and governor valves.

2. In a steam turbine having a rotor and an-elbow steam admission conduit with a first leg arranged at right angles to the turbine axis and a' second leg arranged parallel thereto, a butterfly valve in the first branch and having a trunnion extending upwardly from the latter, a governor valve in the second branch, a rod connected to the governor valve and extending axially of and from the second branch, a governor carried by the rotor and having its operated member arranged for movement axially of the latter, a lever connected to said operated member and having thrust abutting relation with said rod to provide for movement of the latter to move the governor valve in a closing direction and to provide .for movement of the governor valve in a closing direction independently of the governor, a first spring for exerting force on the rod to maintain the latter in abutting relation with respect to said lever and to provide for movement of the governor valve in an opening direction, a second spring'for moving the butterfly valve in a closing a direction, a slide extending parallel to the first branch and at right angles to the turbine rotor, a crank connected to said trunnion, a connection between the slide and the crank and providing for angular movement of the latter with rectilinear movement of the slide, a first latch for holdin the slide in position with the emergency valve open, an overspeed trip devicecarried by the rotor and operative in response to overspeeding of the latter, a rock shaft arranged parallel to the rotor axis, a second lever fixedly carried by the rock shaft and arranged to be moved away from the rotor by the overspeed trip device, a third spring exerting force on the rock shaft to turn the latter in the direction to move said sec-' ondlever-toward the rotor, a first abutment on said rod, a second abutment engageable with the first abutment and movable to move the governor valve in a closing direction, a fourth spring exerting force on the second abutment in the direction of the first abutment, a second latch for holding the second abutment spaced from the first abutment to provide for governor operation of the governor valve uninfiuenced by the fourth spring, and means responsive to movement of the rock shaft by the overspeed trip device to release the first and second latches to provide for closing of the governor and emergency valves.

3. In combination, means providing a fluid passagafirst andsecond valves arranged in series in said passage, first and second biasing means for closing the first and second valves, respectively, a first latch for holding the first valve ope'n'against the force of the first biasing means, means for transmitting motion from the second biasing means to the second valve to close the latter andincluding first, and second parts which are normally disengaged but which are engaged by the second biasingmeans in order that motion may be transmitted from the latter to the second valve to close the latter, a second latch for holding said first part disengaged from the second part with the second biasingmeans biased, a first actuating element, means operated by the first actuating element for releasing the first and second latches, a second actuating element, and means utilizing movement of the second actuating element to move the second valve, in opening and closing directions and including abutment'portions provided on ;the second actuating element and on the second part of said motion-transmitting means and third biasing means acting on the second part to cause it and its abutment portion tofollow the abutment portion of the second actuating element, said second and third biasing means being arranged to exert forces on the second part in opposite directions and the second biasing means being capable of exerting a larger force than the third biasing means in order that itmay move thesecond part against the force of the third biasing means to close the second valve.

4. The, combination as" claimed in claim 3 with means including a lever for moving the first valve from closed position to open position against the force of the first biasing means in order that the first latch may be rendered efiective to hold the valve open with the first biasing means biased and means including a lever for moving said first part of the motion-transmitting means from engaged to disengaged position with respect to the second part thereof in order that the second latch may be rendered effective to hold the first part disengaged with the second 'biasing means biased.

5. In combination, means providing a fluid passage, first and second valves arranged in series in said passage, first and second springs for closing the first and second valves, respectively, a first latch for holding the first valve open against the force of the first spring, means for transmitting motion from the second spring to v the second valve to close the latter and includ' ing first and second parts which are normally disengaged but which are engaged by the second spring in order that motion may be transmitted from the latter to the second valve to close the latter, a second latch for holding the first part disengaged from the second part against the force of the second spring, a first actuating element, means operated by the first actuating element for releasing the first and second latches, a second actuating element, means utilizing movement of the second actuating element to move the second valve in opening and closing directions and including abutment portions provided on the second actuating element and on the second part of said motion-transmitting means and a third springacting on the second part to cause it and its abutment portion to follow the abutment portion of the second actuating element, said second and third springs being arranged to exert forces on the second part in opposite directions and the second spring being stronger than the third spring'in order that it may move the second part against the force of the third springto close the second valve, means including a lever for moving the first valve from closed position to open position against the force of the first spring in order that the first latch may be rendered effective to hold the first valve open against the force of the first spring, the means operated by the first actuating element including a yieldable connection effective in the direction of latching movement of the second latch, and means including a lever for.

moving said first part of the motion-transmitting means from engaged to disengaged position with respect to the second part thereof in order that the second latch may be rendered effective to hold the first part disengaged against the force of the'second spring. 

